Production of an air curtain



June 15, 1955 K. 'r. NORDSTROM ETAL 3,138,936

PRODUCTION OF AN AIR CURTAIN 'Filed April 2, 1963 3 Sheets-Sheet 1 June 1965 K. 'r. NORDSTROM ETAL 3, 88,935

PRODUCTION OF AN AIR CURTAIN Filed-April 2. 1963 5 Sheets-Sheet 2 June 1955 K. 'r. NORDSTROM ETAL 3,133,935

PRODUCTION. OF AN AIR CURTAIN United States Patent 3,188,936 PRODUCTION OF AN AIR CURTAIN Karl Tage Nordstrom and Rosa Aurora Nordstrom, both of Generalsgatan 55, Norrkoping, Sweden Filed Apr. 2, 1963, Ser. No. 270,077 Claims priority, application Sweden, Aug. 6, 1962, 8,582/ 62 10 Claims. (Cl. 98-36) This invention is for improvements in or relating to the production of an air curtain.

It is an object of the present invention to produce an annular, laminar air curtain, and the invention relates to an arrangement by which the intensity of the air curtain can be controlled as required, both as a whole and in its distribution, and the air curtain can be given a convergent or divergent or cylindrical shape and the air in the curtain can be caused to move rectilinearly.

For a better understanding of the invention and to show how the same may be carried into effect, reference may now be made to the accompanying drawings, wherein:

FIG. 1 is a sectioned side view of an embodiment of an arrangement according to the invention;

FIG. 2 illustrates the arrangement shown in FIG. 1, but seen in the direction of the outgoing air curtain, with the cover removed;

FIGS. 3, 4 and illustrate various forms of the partition or rim forming inner wall of the outer annular channel or outer concentric part,

FIG. 6 illustrates another embodiment of an arrangement according to the invention and FIGURE 7 illustrates a part of the embodiment illustrated in FIGURE 1.

Referring to the first embodiment illustrated in FIGS. 1-5, an annular air receptacle 1 has a tangential air inlet 2, a cylindrical inner Wall 3 and a flat base 4 which extends inwardly from the periphery of the receptacle 1 and ends at a distance from the wall 3. A substantially cylindrical rim 5 extends upwardly from the inner edge of the base 4 towards a flat cover 6 of the receptacle 1. The top edge of the rim 5 terminates before the cover 6 at a distance therefrom which varies at different parts of the rim 5. FIGS. 3, 4 and 5 show vaerious embodiments of the top part of the rim 5, all with the common feature that the part 7 nearest the air inlet 2 is the highest and is followed, approximately 90120 from the rear edge of the air inlet 2, by a lower part 8 which extends over approximately from 220- 260 and which is in turn followed by a short part 9 at the original height. The receptacle 1 is thus divided into two concentric annular channels 19, 22 communicating with one another via a relatively narrow, part annular aperture 10 whose width varies at various parts of the periphery. The width of the aperture 10 varies in dependence upon the quantity of air supplied and must be determined empirically, as must also the best embodiment for each particular case of the various parts of the periphery. The bottom of the wall 3 is screwthreaded and receives a ring 11 having a downwardly directed and inwardly convergent surface 26. Between the surface of the ring 11 and the rim 5 are radial straight guide vanes 12 which are attached either to the rim 5 or to the ring 11. An annular plate 13 having a larger external diameter than the rim 5 has a funnel-shaped rim 14 extending from its inner edge, this rim 14 forming with the ring 11, screw-threaded to the wall 3, an outlet aperture 20. The plate 13 is secured to the base 4 of the receptacle 1 by another annular plate 15 which is pressed against the plate 13 by screws 16 so that the rim 14 is displaceable laterally to alter the width of the outlet aperture in the various parts thereof. A wall 18 is disposed behind the air inlet 2 between the rim 5 and outer wall 17 of the receptacle and meets the rim 5 at a tangent in front of the air inlet 2.

The design of the aperture 10 is such that the air pressure throughout the inner annular channel 19 of the receptacle 1 is equal. The width of the annular outlet aperture 20, and therefore the quantity of air discharged, can be controlled by the ring 11 being screwed along the cylindrical inner wall 3. To facilitate empirical determination of the aperture 10, the rim 5 can, conveniently, have a fixed bottom part adapted to receive an interchangeable top part 21.

Referring now to the second embodiment illustrated in FIG. 6, the only differences from the first embodiment are that the bottom of the ring 11 has an inclined downwardly divergent flange 27, and the receptacle 1 has at the bottom an inclined downwardly and outwardly diverging flange 23 having a bent-up edge 24 at its periphery, and the ring 11 has at the bottom a base 25 closing the central aperture. This embodiment has proved very advantageous in cases where the arrangement is used as a bearing element producing an air cushion for hovercraft, whereas the first embodiment has proved very suitable for the removal of grinding dust. A cover 28 is clipped over the central aperture in the annular air receptacle 1 formed by the inner cylindrical wall 3.

Although only two embodiments have been illustrated and described, other embodiments are possible without departing from the scope of the invention.

We claim:

1. An arrangement for producing an annular laminar air curtain comprising an annular air receptacle, a partition dividing said annular air receptacle into an outer and an inner concentric part defining with the Wall of the air receptacle an at least part-annular connecting aperture connecting the two said concentric parts, the width of the partition varying at different parts thereof so that the width of the said connecting aperture varies at different parts thereof, a tangential air entry pipe joining the outer concentric part and an annular outlet aperture provided in the said inner concentric part.

2. An arrangement as claimed in claim 1 wherein radial straight guide vanes are secured to the said partition adjacent the outlet aperture.

3. An arrangement for producing an annular laminar air curtain comprising an annular air receptacle, a partition dividing said annular air receptacle into an outer and an inner concentric part and defining with the wall of the air receptacle an at least part-annular connecting aperture connecting the two said concentric parts, the width of the partition varying at different parts thereof so that the width of the said connecting aperture varies at dilferent parts thereof, a tangential air entry pipe joining the outer concentric part and an annular outlet aperture provided in the said inner concentric part, the annular air receptacle having an externally screw-threaded cylindrical inner wall and a ring in screw-threaded connection therewith, this ring forming the inner wall of the said annular outlet aperture so that adjustment of the ring relative to the inner wall alters the size of the outlet aperture.

4. An arrangement as claimed in claim 3 wherein radial straight guide vanes are secured to the ring adjacent the outlet aperture.

5. An arrangement as claimed in claim 1 wherein the outer wall of the outlet aperture is slidably connected to the inner concentric part for movement in any radial direction to alter the width of the outlet aperture in the various parts thereof.

6. An arrangement as claimed in claim 1 wherein the top part of the partition which defines the said connecting aperture is removably connected to the lower part of the partition so thatthe shape of the connecting aper:

ture' can readily be altered.

7. An arrangement as claimed in claim 1 wherein a wall in the outer concentric part extends from the rear end of the outlet aperture of the air entry pipe; and meets the partition at a tangent 8. An arrangement as claimed in claim 3 wherein the radially outer surface of the ring extends axially and radially inward and the radially outer wall of the outlet aperture is parallel therewith to cooperate therewith; v

in front of said outlet aperture;

9; An' arrangement as claimed in claim 3 wherein the bottom part of the ring takes the form of an inclined References 'Cited by: the Examiner UNITED 'STATES PATENTS 2,341,296 2/44 Slade 9s 40 3,017,664 1/62 'Ladisch 239-470 X ROBERT A. OLEARY, Primary Examiner. 

1. AN ARRANGEMENT FOR PRODUCING AN ANNULAR LAMINAR AIR CURTAIN COMPRISING AN ANNULAR AIR RECEPTACLE, A PARTITION DIVIDING SAID ANNULAR AIR RECEPTACLE INTO AN OUTER AND AN INNER CONCENTRIC PART DEFINING WITH THE WALL OF THE AIR RECEPTACLE AN AT LEAST PART-ANNULAR CONNECTING APERTURE CONNECTING THE TWO SAID CONCENTRIC PARTS, THE WIDTH OF THE PARTITION VARYING AT DIFFERENT PARTS THEREOF SO THAT THE WIDTH OF THE SAID CONNECTING PARTS THEREOF AT DIFFERENT PARTS THEREOF, A TANGENTIAL AIR ENTRY PIPE JOINING THE OUTER CONCENTRIC PART AND AN ANNULAR OUTLET APERTURE PROVIDED IN THE SAID INNER CONCENTRIC PART. 